Hi. It really depends what sort of ROM you're looking for. Ultimately the best thing to do is to try 2 or 3 different ones out and see which one you like best!
If you want a ROM that is very similar to how your phone is at the moment, you should get a sense ROM.
Sense is basically HTC's own UI on their phones (on android phones, the UI is called the 'launcher')
Android Revolution has always been great, but actually I'd say the very best sense rom at the moment is one called SmartDroid.
Away from sense, you can look at cyanogenmod and miui. With MIUI builds, just pick one off XDA, there's not much difference between them.
With cyanogenmod, I'd recommend you look at IceColdSandwich.
Here's a link to the forum with all the roms:
http://forum.xda-developers.com/forumdisplay.php?f=765
Do they all offer better battery life and more customization etc?
YES! In terms of battery though, although you can underclock and undervolt the cpu on a rooted phone to save battery, most of the battery drain comes from your own personal useage and apps rather than the ROM or firmware of the phone.
